1. Field
Embodiments of the present invention relate to an assembly structure of a coil assembly of a solenoid valve and an electronic control unit for an electronic brake system that may enhance electromagnetic interception and heat dissipation.
2. Description of the Related Art
Various kinds of brake systems have been proposed to produce braking force for a vehicle. Example of the brake systems include an anti-lock braking system (ABS), which prevents slippage of a vehicle, an electro hydraulic braking (EHB) system, and an electronic stability control (ESC).
An electronic braking system as above includes a hydraulic control unit (HCU) including a plurality of solenoid valves to adjust hydraulic braking pressure transferred to a wheel brake, a low-pressure accumulator to temporarily store oil, a pump to forcibly pump out oil stored in the low-pressure accumulator, and a high-pressure accumulator to reduce pressure pulsation of the oil pumped out by the pump, and an electronic control unit (ECU) to control electrically operated constituents.
The ECU is equipped with a printed circuit board (PCB) and joined to the HCU by fastening members such as bolts to control electrically operated constituents. In addition, each of the solenoid valves includes a coil assembly provided with a wound coil to produce an electromagnetic field when electrical power is applied thereto, and a valve assembly to open and close an internal flow channel according to the electromagnetic field produced by the coil assembly. Herein, the coil assembly is installed in the ECU such that a lead wire arranged in the coil assembly contacts the PCB. A part of the valve assembly is fitted into the center of the coil assembly, and the other part of the valve assembly is press-fitted into the HCU formed of aluminum.
Herein, a structure to intercept electromagnetic waves is provided between the ECU and the HCU to allow smooth operation of the solenoid valves, which are electrically operated. For example, a ground spring allowing contact between the PCB and a counterpart metallic component is mounted, or the solenoid valves are arranged to contact the PCB through a separate connection member, in order to intercept electromagnetic waves.
In addition, to dissipate heat generated in the coil assembly when power is applied, a separate elastic member is used to maintain the housing of the coil assembly in a close contact with the HCU to make the coil assembly contact the HCU.
An electronic brake system configured as above intercepts electromagnetic waves to smoothly control, through the ECU, operation of respective constituents, particularly, the solenoid valves. In addition, the electronic brake system dissipates heat generated in the coil assembly to prevent the generated heat from causing malfunction to ensure stable braking operation.
However, since separate members need to be provided to form the structure of contact between the ECU and the HCU for the electromagnetic interception and heat dissipation, costs of manufacture of the brake system may increase and manufacturability of the brake system may be degraded. Researches are being conducted to enhance the assembly structure between the ECU and the coil assembly and between the coil assembly and the HCU in order to reduce manufacturing costs and enhance electromagnetic interception and heat dissipation.